diff options
Diffstat (limited to 'doc/scan.n')
| -rw-r--r-- | doc/scan.n | 82 |
1 files changed, 54 insertions, 28 deletions
@@ -55,6 +55,7 @@ conversion character is \fB[\fR or \fBc\fR). Then it converts the next input characters according to the conversion specifier and stores the result in the variable given by the next argument to \fBscan\fR. +.SS "OPTIONAL POSITIONAL SPECIFIER" .PP If the \fB%\fR is followed by a decimal number and a \fB$\fR, as in .QW \fB%2$d\fR , @@ -66,8 +67,8 @@ specifiers must be positional. Every \fIvarName\fR on the argument list must correspond to exactly one conversion specifier or an error is generated, or in the inline case, any position can be specified at most once and the empty positions will be filled in with empty strings. +.SS "OPTIONAL SIZE MODIFIER" .PP -.VS 8.5 The size modifier field is used only when scanning a substring into one of Tcl's integer values. The size modifier field dictates the integer range acceptable to be stored in a variable, or, for the inline @@ -82,26 +83,36 @@ modifier. Either one indicates the integer range to be stored is limited to the same range produced by the \fBwide()\fR function of the \fBexpr\fR command. The \fBll\fR size modifier indicates that the integer range to be stored is unlimited. -.VE 8.5 +.SS "MANDATORY CONVERSION CHARACTER" .PP The following conversion characters are supported: -.TP 10 +.TP \fBd\fR +. The input substring must be a decimal integer. It is read in and the integer value is stored in the variable, truncated as required by the size modifier value. -.TP 10 +.TP \fBo\fR +. The input substring must be an octal integer. It is read in and the integer value is stored in the variable, truncated as required by the size modifier value. -.TP 10 +.TP \fBx\fR +. The input substring must be a hexadecimal integer. It is read in and the integer value is stored in the variable, truncated as required by the size modifier value. -.TP 10 +.TP +\fBb\fR +. +The input substring must be a binary integer. +It is read in and the integer value is stored in the variable, +truncated as required by the size modifier value. +.TP \fBu\fR +. The input substring must be a decimal integer. The integer value is truncated as required by the size modifier value, and the corresponding unsigned value for that truncated @@ -109,32 +120,37 @@ range is computed and stored in the variable as a decimal string. The conversion makes no sense without reference to a truncation range, so the size modifier \fBll\fR is not permitted in combination with conversion character \fBu\fR. -.TP 10 -\fBi\fR +.TP +\fBi\fR +. The input substring must be an integer. The base (i.e. decimal, binary, octal, or hexadecimal) is determined in the same fashion as described in \fBexpr\fR. The integer value is stored in the variable, truncated as required by the size modifier value. -.TP 10 +.TP \fBc\fR +. A single character is read in and its Unicode value is stored in the variable as an integer value. Initial white space is not skipped in this case, so the input substring may be a white-space character. -.TP 10 +.TP \fBs\fR +. The input substring consists of all the characters up to the next white-space character; the characters are copied to the variable. -.TP 10 +.TP \fBe\fR or \fBf\fR or \fBg\fR +. The input substring must be a floating-point number consisting of an optional sign, a string of decimal digits possibly containing a decimal point, and an optional exponent consisting of an \fBe\fR or \fBE\fR followed by an optional sign and a string of decimal digits. It is read in and stored in the variable as a floating-point value. -.TP 10 +.TP \fB[\fIchars\fB]\fR +. The input substring consists of one or more characters in \fIchars\fR. The matching string is stored in the variable. If the first character between the brackets is a \fB]\fR then @@ -145,8 +161,9 @@ contains a sequence of the form \fIa\fB\-\fIb\fR then any character between \fIa\fR and \fIb\fR (inclusive) will match. If the first or last character between the brackets is a \fB\-\fR, then it is treated as part of \fIchars\fR rather than indicating a range. -.TP 10 +.TP \fB[^\fIchars\fB]\fR +. The input substring consists of one or more characters not in \fIchars\fR. The matching string is stored in the variable. If the character immediately following the \fB^\fR is a \fB]\fR then it is @@ -158,11 +175,12 @@ character between \fIa\fR and \fIb\fR (inclusive) will be excluded from the set. If the first or last character between the brackets is a \fB\-\fR, then it is treated as part of \fIchars\fR rather than indicating a range value. -.TP 10 +.TP \fBn\fR +. No input is consumed from the input string. Instead, the total number of characters scanned from the input string so far is stored in the variable. -.LP +.PP The number of characters read from the input for a conversion is the largest number that makes sense for that particular conversion (e.g. as many decimal digits as possible for \fB%d\fR, as @@ -192,7 +210,9 @@ modifier has no \fBsscanf\fR counterpart. If the end of the input string is reached before any conversions have been performed and no variables are given, an empty string is returned. .SH EXAMPLES +.PP Convert a UNICODE character to its numeric value: +.PP .CS set char "x" set value [\fBscan\fR $char %c] @@ -200,6 +220,7 @@ set value [\fBscan\fR $char %c] .PP Parse a simple color specification of the form \fI#RRGGBB\fR using hexadecimal conversions with substring sizes: +.PP .CS set string "#08D03F" \fBscan\fR $string "#%2x%2x%2x" r g b @@ -208,60 +229,65 @@ set string "#08D03F" Parse a \fIHH:MM\fR time string, noting that this avoids problems with octal numbers by forcing interpretation as decimals (if we did not care, we would use the \fB%i\fR conversion instead): +.PP .CS set string "08:08" ;# *Not* octal! if {[\fBscan\fR $string "%d:%d" hours minutes] != 2} { - error "not a valid time string" + error "not a valid time string" } # We have to understand numeric ranges ourselves... if {$minutes < 0 || $minutes > 59} { - error "invalid number of minutes" + error "invalid number of minutes" } .CE .PP Break a string up into sequences of non-whitespace characters (note the use of the \fB%n\fR conversion so that we get skipping over leading whitespace correct): +.PP .CS set string " a string {with braced words} + leading space " set words {} while {[\fBscan\fR $string %s%n word length] == 2} { - lappend words $word - set string [string range $string $length end] + lappend words $word + set string [string range $string $length end] } .CE .PP Parse a simple coordinate string, checking that it is complete by looking for the terminating character explicitly: +.PP .CS set string "(5.2,-4e-2)" # Note that the spaces before the literal parts of # the scan pattern are significant, and that ")" is # the Unicode character \eu0029 if { - [\fBscan\fR $string " (%f ,%f %c" x y last] != 3 - || $last != 0x0029 + [\fBscan\fR $string " (%f ,%f %c" x y last] != 3 + || $last != 0x0029 } then { - error "invalid coordinate string" + error "invalid coordinate string" } puts "X=$x, Y=$y" .CE .PP -.VS 8.5 An interactive session demonstrating the truncation of integer values determined by size modifiers: +.PP .CS -% set tcl_platform(wordSize) +\fI%\fR set tcl_platform(wordSize) 4 -% scan 20000000000000000000 %d +\fI%\fR scan 20000000000000000000 %d 2147483647 -% scan 20000000000000000000 %ld +\fI%\fR scan 20000000000000000000 %ld 9223372036854775807 -% scan 20000000000000000000 %lld +\fI%\fR scan 20000000000000000000 %lld 20000000000000000000 .CE -.VE 8.5 .SH "SEE ALSO" format(n), sscanf(3) .SH KEYWORDS conversion specifier, parse, scan +'\" Local Variables: +'\" mode: nroff +'\" End: |